A single-unit: is only ONE unit (e.g., apartment, villa, studio, etc.). You add the description of the unit and it is booked as a single entity.

Multi-unit

A multi-unit: is a group of units sharing the same address and amenities (e.g., a number of apartments in the same building or chalets in the same resort). You add the common features of the units followed by the distinguishing characteristics of each).